1. Field of the Invention
The present invention relates to an optical fiber termination module for use in an array of modules for terminating the optical fibers of a cable, and in one aspect to an optical fiber module for use in a panel with an array of modules to be connected to optical fiber distribution lines.
2. Description of the Prior Art
The prior art has a variety of panel configurations for connecting the optical fibers in an incoming cable to the connectors and managing the slack cables and splice structures incorporated in the panels. One such patent of the assignee of this application is U.S. Pat. No. 4,824,196.
The present invention is directed at a simplified version of supporting a plurality of termination modules in an array and packaging the array of modules for use in terminating a small number of optical fibers, such as in an apartment building or in a single family residence, or in a factory or office work station. The prior art panels in some instances may be modular to afford their use with a small number of fibers but by and large they are adapted to the large termination situations where many optical fibers are terminated. In the present environment it is necessary that the distribution fiber be capable of being connected and disconnected without calling a technician. Yet there are only a small number of fibers and they therefore should be conveniently packaged to permit one of limited assembly skill to make the connections and disconnections of the distribution fibers from the transmission lines coming into the residence or work station. A skilled technician will generally make the splice between the incoming fiber and the panel connector and then one with minimal assembly skill can make the connection to the panel connector. The splice to the pigtail of a connector plug is made by a device which can be applied by a skilled technician in the field, who cleaves the fiber, abuts two fiber ends and joins the ends together permanently by a splice. The connector includes connector plugs, a coupling and connector plug which plugs are applied to a length of optical fiber which is carefully prepared and aligned in a fixed position in the plug of the connector in an assembly plant or as a field operation requiring special equipment and great care to terminate the fiber precisely. This plug and fiber end may then be readily connected to the end of another fiber which is terminated in a connector plug in a connector coupling which mates and aligns the ends of the fibers in the plugs to each other. This can be accomplished by anyone with minimal assembly skills. The skilled technicians then are the workers with the responsibility of taking the optical fiber cable that has arrived at the termination station and separating the individual optical fibers and then splicing them to a fiber end leading from a connector plug. The plugs are subsequently connected to a connector coupling for connection to a plug on a fiber running to an opto-electronic piece of equipment. When this piece of equipment is a piece of equipment in the home, apartment or factory or office work station and the number of optical fibers are all contained in a single cable, or the cable contains optical fibers together with copper signal wires, it is desirable to have a convenient means of termination of the optical fibers as well as a convenient method of joining the copper wires to a distribution wire. This type of termination should not require any more skill than the technician that would routinely service and install telephone or electrical power. If it requires tools that cut and polish the optical fiber end and special fixtures to secure the finished fiber end in a plug, then the level of skill required to make only several connections at remote locations is economically and commercially disadvantaged, and the optical fiber distribution system will not grow and be as readily available to as many citizens as rapidly as desired.
Presently, where large installations are made in a building or central station, a distribution housing is installed and the cable is brought in for distribution. Individual optical fibers from the cable are spliced to long pigtails, each consisting of individually jacketed optical fiber terminated into a connector plug at one end. The pigtail connector plug is mounted into a connector coupling located within the distribution housing or a remote second distribution housing. The splice joining the two fibers is placed within a splice holder within the first distribution housing. The surplus fiber from the pigtail and surplus fiber from the cable are both carefully stored in the distribution housing. A second plug mates with the first plug in the connector coupling and routes to an opto-electronic device or other intermediate junction. This is the routine which must be followed to allow slack for removal of the fiber from the distribution housing for application of a plug, either as a precise field cut and polish operation or through splicing of a factory made plug with a fiber pigtail.
A prior device, identified as an optical cable header is described in U.S. Pat. No. 4,585,303. This device utilizes a plurality of optical connector supports which are engaged in a magazine or housing. The connector supports have an elongate body in the form of a hollow finger. The finger has a cylindrical connector member at a front end and a side mounted former upon which to wind a length of fiber located near to its opposite or rear end. The magazine has a row of cavities which are open at the rear of the magazine for receiving the supports and have circular openings in the front wall to receive the connector members on the connector supports when they are received in the cavities. In FIGS. 7-11 the optical connector support includes a finger, constituted by a rigid metal blade formed of elongate U shape. The optical connector is mounted in the bottom of the U to receive the end fitting of a fiber inside the finger. The optical connector will also receive an analogous end fitting of an external fiber for connection to the fiber inside the finger. The connector described in the introduction is an installed connection end fitting, for example the one described in French patent 2 275 787 and patent of addition 2 316 611, the earliest patent corresponding generally to U.S. Pat. Nos. 3,989,567 and 4,050,783. This connector is designed to receive one or multiple fibers, but to receive one fiber, requires an installation and in each end fitting, the end face of a fiber is rectified and suitably positioned for providing accurate optical connection when two connection fittings are brought together. The installation of the end fitting is not perceived as a field installation since U.S. Pat. No. 4,585,303 refers to the cable having a plurality of optical fibers with each fiber having a connection end fitting installed on its end. The purpose of the patented header is to avoid having to interrupt the connection of several fibers as with the connector of U.S. Pat. No. 4,050,783, when repairing a defect in the connection between any one pair of fibers. Further, after the supports are placed in the magazine, the connector members on the front face of the magazine are aligned in a row and are not readily accessible to make the desired connections.
Another mounting panel with means for supporting a plurality of connectors is shown in U.S. Pat. No. 4,752,110. This patent shows a cabinet for supporting incoming fibers, slack in those fibers, splices, connectors and pigtail fibers, and the plugs for the distribution fibers. This is typical of the prior art and is too bulky and unnecessarily complicated to provide the termination in the residence, apartment or at the work station.
The purpose of the present invention is to provide a module which allows splicing of a fiber to a connector plug pigtail within the module, thus eliminating the need for excess slack between the splice and plug, and between the splice and the balance of the feeder system as formerly required to remove the splice to a location suitable for the precise operation required.
Reliable mechanical splices of several designs have recently become available which make this splicing within the module possible.
It is therefore an object of this invention to provide a termination which will reduce the need for large or bulky boxes to handle incoming and connector fibers to afford the installation of optical fibers into a residence, apartment or work station and connection of the incoming optical fibers to opto-electronic equipment.
It is a further object of the present invention to provide a module which can be coupled to the end of the incoming fiber readily in the field by the skilled technician to terminate the transmission cable. This module is then packaged in an array wherein the modules are in side-by-side relationship to fit in a compact panel, in an array with other modules, in such a manner as to afford ready access to the individual connectors for attachment of the plugs on the distribution fibers by a relatively unskilled assembler.